The flywheel has to be changed, will need a stator ring for charging system,add starter,wiring,battery. It would be easier and almost as cheap to just buy a different engine. The twin cylinder Kaws pull start very easy.

Light weight oil will make no difference at all. I have had a Kaw 14 hp single since 1998. Its been a ***** to start in the morning when the temp is under 45 degrees since it was new. They just pull hard. If its a hydro like mine is you really need to open the bypass on the pumps. And it was checked by the shops more than once.